1. Field of the Invention
The present invention relates to linear slides with rolling elements generally and, more particularly, but not by way of limitation, to a novel linear slide having reduced friction.
2. Background Art
The present invention relates to linear slides with rolling elements which linear slides consist generally of a base, a carriage, rails, rolling elements (balls or rollers), and end plates. These slides are widely used in instrumentation, machine tools, and other similar applications where precision linear movements are required.
Conventional designs of such slides, especially in high accuracy applications, however, still need reduction of friction. The problem of increased friction stems from the fact that during the movement of rolling elements, rigid retainers create unnecessary interference between individual movements of the rolling elements which differ somewhat from the movement of the whole group of rolling elements.
With increased length of slides (and, therefore, the number of rolling elements), the forces involved in such interference become progressively greater which, in addition, results in fast wear of the retainers.
Another problem, non-uniformity of friction which is typical of conventional slides is caused by the fact that the rolling elements (which are held together in groups by retainers), tend to creep eventually toward one of the ends of the slide during its service. Then, they abruptly hit against the end plate or the stop before completion of a stroke, causing the retainer(s) to push the whole group of rolling elements to the end of a stroke without actually rolling. With the combination of a load and a preload, sliding friction developed at such a moment can be ten or more times greater than the regular rolling friction typical of the slide. This fact may result in the malfunction, or even breakage, of the equipment in which the slide is used.
Another mutual disadvantage of conventional slides is the reduced number of rolling elements because of the use of retainers and, therefore, reduced load capacity and rigidity.
Still another disadvantage of prior art is difficulty of repair, since replacement of retainers takes disassembly of the whole unit which destroys preload adjustment of the slide.
Accordingly, it is a principal object of the present invention to provide for a reduced friction linear slide which avoids the disadvantages of conventional slides.
It is a further object of the invention to provide such a linear slide which includes no rigid retainers.
It is an additional object of the invention to provide such a linear slide which avoids sliding friction between the elements thereof.
It is another object of the invention to provide such a linear slide which has a increased number of rolling elements for a given length.
It is yet a further object of the invention to provide such a linear slide which is economically manufactured.
It is yet an additional object of the invention to provide such a linear slide which is easily repaired.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.